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A more accurate prenatal test to predict Down syndrome

Screening looks at baby’s DNA in mother’s blood

5:00pm, April 1, 2015
Prenatal Test

PUT TO THE TEST  Prenatal blood tests that analyze fetal DNA are more reliable than standard screening methods for detecting whether babies carry certain extra chromosomes that can cause birth defects.

A prenatal test that examines a baby’s DNA in a sample of the mother’s blood is much more accurate for detecting Down syndrome for most women than standard screening methods are.

In a study of 15,841 pregnant women, babies identified by the DNA test as having an extra copy of chromosome 21 had an 80.9 percent chance of actually having Down syndrome. In comparison, only 3.4 percent of babies that tested positive with standard screening methods had Down syndrome, an international team of researchers report online April 1 in the New England Journal of Medicine.

In the United States, one in 691 babies is born with Down syndrome. Standard screening methods include ultrasound and maternal blood tests that measure certain proteins. If these methods indicate a problem, doctors may perform more invasive tests, such as amniocentesis, which can raise the risk of miscarriage. More accurate screening

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